How to Verify If Last Summer's Sunscreen Is Still Effective

Sunlight is essential for vitamin D production, which supports calcium absorption and bone health, and it can improve mood. However, exposure to ultraviolet A (UVA), ultraviolet B (UVB) and infrared radiation can cause burns, premature skin aging, dermatitis and even skin cancer.

Health experts recommend using a sunscreen with a minimum SPF 30 and applying it generously—about 2 mg per cm² of skin, which translates to roughly 30 ml for a full‑body application for an adult. Most people apply only about half that amount, so using a product labelled SPF 30 or higher and re‑applying every two hours is advised. Dermatologists suggest checking the expiration date and visual condition of a sunscreen from the previous summer before re‑using it, and to apply it before swimming or beach activities.

Additional protective measures include avoiding peak sun hours (12 – 17 h), using physical barriers such as hats, umbrellas and clothing, wearing sunglasses and staying well‑hydrated.